Process of making paper from straw and product



Patented July 5, 1927.

UNITED STATES PATENT OFFICE.

CHARLES D. WOOD, OF CLEVELAND, OHIO, ASSIGNOR TO THE GRASSELLI CHEMICALCOMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

PROCESS OF MAKING PAPER FROM STRAW AND PRODUCT.

No Drawing.

In an application, Serial No. 81,828, filed January 12, 1926, in thename of Charles D. Wood and Edward A. Taylor, there is described andclaimed a process for the production of paper pulp from straw andsimilar fibrous vegetable materials, which consists essentially indigesting the straw with a solution containing as the essential reagentssodium sulfid and sodium hydroxid. The process described in saidapplication is characterized by the use of only a relatively dilutesolution of the reagent, up to about one percent, and only a relativelysmall quantity of reagent as com ared with the quantity used in theso-calle Kraft process, i. e., the combined weights of the sodium sulfidand the sodium hydroxid amount to only about' l to 6 percent of theweight of the straw treated, and by the use of the sodium sulfid andsodium hydroxid in relative proportions in the neighborhood of 3 partsby weight of sodium sulfid to 5 parts by weight of sodium hydroxid, andby the fact that the cooking operation is generally completed in 3 to 4hours. The cooking operation is carried out by digesting the straw withthe solution of the reagent in a closed digestor with steam at apressure of 30 to pounds per square inch; The process of saidapplication gives a stock which may be beaten and washed in one to twohours as compared with five to six hours required for lime stock, andthe resulting pu p may be made into paper of superior pro erties.

he present invention relates to the production of paper from stock suchas that produced by the process of -said application, and moreparticularly to the use of soluble constituents of the straw as abinding and sizing agent for the pulp in the production of papertherefrom.

In the manufacture of paper from pulp it is necessary in order to securemaximum strength to add sizing agents orbinders.

I have found that the soluble components of the straw present in thedigestor liquor pro- 'duced in e digestion of-the straw may be used forthis-purpose and the supplying of sizin and binding material from anexterna source thus dispensed with.

. In the investigation of the properties of the soluble constituents ofthe straw, i. e., the portion of the straw dissolved b di esting it asdescribed with a solution 0 so ium Application filed January 12, 1926.Serial No. 80,813.

sulfid and sodium hydroxid, the following properties have beendetermined:

(1) The digestor liquids contain 3 to 4 percent of dissolved solids.

(2) The dissolved solids are precipitated by acids, only enough acidbeing required to give a slightly acid reaction with methyl orange.

(3) The precipitated solids are practically insoluble in water, slightlysoluble in concentrated hydrochloric acid and dilute sulfuric acid,decomposed byvconcentrated sulfuric acid and completely soluble inalkalies.

(4) The solids have adhesive properties and are regarded as beingprincipally the natural binding material of the straw.

A consideration of the properties of the dissolved solids in thedigestor liquors led to the conjecture that they might be made, to serveas a binding or sizing and water- 7 proofing agent in paper ma e fromthe straw pulp, which con ecture was Proved to be correct.

-A preferred procedure in accordance with my invention is to pulp thestraw-stock directly, that is, withoutthe usual washing and separationof the di estor li uors, and then neutralize the pulp the a dition ofacid to preci itate the dissolved solids in the pulp. T e pulp is thenworked into paper in the usual way. This procedure is preferred becauseit eliminates the usual washing of the stock in the beaters, thussimplifying the conversion of the stock into pulp, and provides abinding or sizing agent for the ulp without resort to an external supplyt ereof, and besides disposes of the digestor liquors. It is apparent,however, that the alkali-soluble components of straw may be utilized asthe binding agent for 5 the pulp in the production of paper in otherways. For instance, the digestor llquors may be separated from the stockb draining or centrifuging the stock was ed and ulped in the usual way,the dissolved solids 1 1n the digestor liquors recovered byacidification and redissolved in alkali, the resultin solution added tothe pulp, and the disso ved solid recipitated in the pulp byacidification. t is also apparent that all of the dissolved solids inthe digestor-1i uors need not be used, that is, a portion 0 the digestorliquors may; be separated from the stock before it is ulped, or thestock may be partially wash or only a portion of the pulp. It is furtherunderstood that my in- I vention does not preclude the use of otherbinding or sizing agents in conjunction with the dissolved solids in thedigestor li uors. Moreover, the invention is not limite excepting as isindicated by the appended claims, to the use of stock prepared by theparticular cooking method referred to, but is applicable to any paperstock prepared by a cooking process which dissolves a component of theraw fibrous material capable of reprecipitation and having sizing orbinding properties. In the so-called lime-process, according to whichstraw is digested with lime water, the digestor liquors .are practicallyfree of dissolved solids and my process therefore is not applicable tolimestock, but it is applicable to stocks prepared by cooking'straw andthe like in alkaline agents. such as caustic soda, capable of dissolving.the alkali-soluble gnatural binding agent of the fibrous material.

It is noted that in the process of the said application the quantity ofreagent used in cooking the straw is limited so that at the end of thecooking operation there is practically no free reagent left in thedigestor liquor, and that my preferred process of working thestockdirectly into pulp without separation of the liquor is applicable tosuch stock. In other cases, however, as in the case of stock prepared bythe so-called Kraft process, in which an excess of reagent is used, aprocedure involving the separation of the digestor liquor from thestock, recovery of the soluble binding material from the liquor byprecipitation, resolution of the material in alkali and addition of theresulting solution to the pulp, must be re sorted to in order toseparate the soluble components of the fibrous material from the excessof reagent. Other variations of the process to adapt it to differentconditions encountered in the preparation of the pulp will be apparentfrom a consideration of the foregoing disclosure of the principles of myinvention, the preferred embodiment of which, as stated, is the pulpingof a stock directly with the digestor liquors or a portion thereofprepared by digestin straw or similar fibrous vegetable materia in adilute solution of sodium sulfid and sodium hydroxid, in quantityamounting to only about 4 to 6 percent of the weight of the fibrousmaterial in accordance with the processof the prior application referredto.

Paper prepared from straw stock using the soluble components as thebinding or sizing agent in accordance with my invention, as comparedwith other straw paper,

posseses a satisfactory strength, is. highly sized and water-proofed andis readily colored and bleached.

I claim:

1. Process of making paper from straw and similar fibrous vegetablematerials, which comprises incorporating the alkali soluble componentsof the fibrous material obtained by digesting the fibrous material withan alkaline reagent comprising a soluble sulfide with a pulp derivedfrom said fibrous material.

2. Process of making paper from straw and similar fibrous vegetablematerials, which comprises incorporating a solution of the alkalisoluble components of the fibrous material obtained by digesting thefibrous material with an alkaline reagent comprising a soluble sulfidewith a pulp derived from said material and neutralizing the resultingpulp.

3. Process of making paper from straw and similar fibrous vegetablematerials, which comprises digesting said fibrous ma terials in analkaline reagent com rising a .soluble sulfide, working the resultlngstock with a part at least of the digestor liquors into a pulp, andneutralizing the pulp.

4. Process of making pulp from straw and similar fibrous vegetablematerials,-

which comprises digesting said materials in a solution containing sodiumsulfid and sodium hydroxid, working the resulting stock and a part atleast of the digestorliquors into a pulp and neutralizing the 111 I p 5%Process of making paper from straw and similar fibrous vegetablematerials, which comprises incorporating in a pulp of said materialsalkali soluble material dissolved therefrom by di estion in a solutioncontaining sodium s'ul d and sodium hydroxid.

6. Paper comprising the fibrous structure of straw and a binding orsizing material obtained by digesting straw with an alkaline reagentcomprising a soluble sulfide.

. In testimony whereof, I afiix my signature.

CHARLES D. WOOD.

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